The ethernet thing seems lame however. Why must you buy a special card? They should have just left it off and instead given you another USB port in my view.
1) It's a proprietary adapter because the laptop's too slim for an RJ45.
2) It's onboard because you can't PXE boot it from Wi-Fi
3) External USB docks/NICs could also fix #2, but since each dock/NIC has a distinct MAC, you can't have a nice 1:1 MAC:Workstation relationship for provisioning via PXE anyways
#2 and #3 are what prevented our company from bulk-ordering the first generation as our go-to office laptop, since its lack of on-board ethernet wouldn't work cleanly with MS SCCM, which was a shame, since it hit every other need pretty perfectly.
That isn't a technical limitation of Wi-Fi or PXE. For it to work the Wi-Fi has to be setup as part of the pre-boot environment (BIOS/UEFI). For example as far as I can tell my Mac mini can do this.
Given that Lenovo like to pull authorization stunts with internal wifi cards (refusing to work with models that aren't blessed) they could make this work.
Admittedly, there's not a standardized way to do it either:
Macs actually save Wi-Fi AP details into SMC or NVRAM (can't recall which) which is why wireless connectivity is accessible without setup when in the BIOS and recovery modes, but there's no analogous part in standard IBM-compatible PCs.
Speculating, but this avenue could hypothetically be a security issue too if it's not secured well: attackers could extract confidential AP details without having to bypass full-disk encryption, or attack live RAM.
EFI variables are persistent and accessible from the pre-boot environment.
Why they give you a special plug rather than USB, I don't know. I could speculate- for example, USB 2.0 is 480Mbps, which means you cannot have 1Gbps ethernet without a special USB 3.0 adapter.
Interesting note re: RAM choices ... if you select the i5-5200U CPU on the Lenovo US website then you are allocated 4GB of RAM and have no option to select 8GB. The mid-range CPU (i5-5300U) allows you to select either 4GB or 8GB. Finally, if you select the i7-5600U then you are allocated 8GB and can't select 4GB.
The customization page on their website only allowed 8GB of memory and the user manual explicitly stated that the maximum RAM was 8GB. I bought 16GB after reading users reporting that it worked fine, and I can confirm: it works fine. I push it to the limit all the time.
Then again, it might just be that new RAM chips came out after the laptop did, and I might just be conspiracy-theorizing.
Which begs the question, could they have offered a 16GB option?
Because an ethernet port is bigger than that computer.